Host for controlling non-volatile memory card, system including the same, and methods operating the host and the system

ABSTRACT

A host for controlling a non-volatile memory card, a system including the same, and methods of operating the host and the system are provided. The method of operating the host connected with the non-volatile memory card through a clock bus, a command bus, and one or more data buses includes transmitting a first command to the non-volatile memory card through the command bus, transmitting first data corresponding to the first command to the non-volatile memory card through the one or more data buses or receiving the first data from the non-volatile memory card through the data buses, and transmitting a second command to the non-volatile memory card at least once through the command bus during or before transfer of the first data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) from KoreanPatent Application No. 10-2012-0102484 filed on Sep. 14, 2012, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

Example embodiments of the inventive concepts relate to a host forcontrolling a non-volatile memory card, and more particularly, to a hostfor increasing read/write performance of the non-volatile memory card, asystem including the same, and method of operating the host and thesystem.

A multimedia card (MMC) is a representative one of non-volatile memorycards. The MMC is a flash memory card standard. An eMMC is an embeddedMMC standard defined by the Joint Electron Devices Engineering Council(JEDEC). With eMMC, communication is based on a 10-signal bus. The eMMCmay be embedded in mobile communication devices like smart phones.

SUMMARY

According to some example embodiments of the inventive concepts, thereis provided a method of operating a host connected with a non-volatilememory card through a clock bus, a command bus, and one or more databuses. The method includes transmitting a first command to thenon-volatile memory card through the command bus, transmitting firstdata corresponding to the first command to the non-volatile memory cardthrough the one or more data buses or receiving the first data from thenon-volatile memory card through the one or more data buses, andtransmitting a second command to the non-volatile memory card at leastonce through the command bus during or before transfer of the firstdata.

The second command may be transmitted when the non-volatile memory cardis in a busy state.

The busy state of the non-volatile memory card may be indicated by oneof the one or more data buses.

The method may further include operating a command bus state machine formanaging states of the command bus and operating a data bus statemachine for managing states of the one or more data buses independentlyfrom the command bus state machine. The states of the one or more databuses may include an idle state, a data transfer state, and areceive-response or wait state. The second command may be transmitted tothe non-volatile memory card when a state of the one or more data busesis the data transfer state or the receive-response or wait state.

The first command may be a command accompanied by data and the secondcommand may be a command that is not accompanied by data.

The method may further include managing the number of transmission timesof the second command.

According to other example embodiments of the inventive concepts, thereis provided a method of operating a non-volatile memory card systemincluding a host connected with a non-volatile memory card through aclock bus, a command bus, and one or more data buses. The methodincludes the host transmitting a first command to the non-volatilememory card through the command bus; transferring first datacorresponding to the first command between the host and the non-volatilememory card through the one or more data buses; and the hosttransmitting a second command to the non-volatile memory card throughthe command bus during the transfer of the first data.

The method may further include the non-volatile memory card sequentiallyreceiving a plurality of second commands and storing them in a commandregister. The transmitting the second command to the non-volatile memorycard may include the host transmitting the plurality of second commandsof the same type to the non-volatile memory card.

Each of the second commands may be a prepare-read command including adata size indicating a size of data to be read and a start address. Thedata size and the start address may be stored in the command register.

The method may further include the non-volatile memory card reading datafrom a non-volatile memory and storing the data in a data bufferincluded in the non-volatile memory card in response to each secondcommand.

The method may further include the host transmitting a third command tothe non-volatile memory card; and the non-volatile memory cardtransmitting the data stored in the data buffer to the host in responseto the third command.

The method may further include the host transmitting a cancel commandfor specifically cancelling all or some of the plurality of secondcommands to the non-volatile memory card; and the non-volatile memorycard invalidating the all or some of the second commands specified bythe cancel command or data corresponding to the specified all or some ofthe second commands in response to the cancel command.

Each of the second commands may be a prepare-write command including adata size indicating a size of data to be written and a start address.

The method may further include the host transmitting second datacorresponding to a first second command among the plurality of secondcommands to the non-volatile memory card through the one or more databuses; the non-volatile memory card receiving and programming the seconddata to the non-volatile memory in response to the first second command;the host transmitting a second command among the plurality of secondcommands to the non-volatile memory card while the second data is beingtransmitted through the one or more data buses; the host transmittingthird data corresponding to the second command to the non-volatilememory card through the one or more data buses after the second data iscompletely transmitted; and the non-volatile memory card receiving andprogramming the third data to the non-volatile memory in response to thesecond command.

According to further example embodiments of the inventive concepts,there is provided a host connected with a non-volatile memory cardthrough a clock bus, a command bus, and one or more data buses. The hostincludes a processor configured to control overall operation of the hostand a host controller configured to be electrically connected with theprocessor and to interface with the non-volatile memory card.

The host controller may transmit a first command to the non-volatilememory card through the command bus, transmit first data correspondingto the first command to the non-volatile memory card through the databus or receive the first data from the non-volatile memory card throughthe one or more data buses, and transmit a second command to thenon-volatile memory card through the command bus during or beforetransfer of the first data.

According to example embodiments of the inventive concepts, a method ofoperating a host connected to a non-volatile memory includestransmitting a first command from the host to the non-volatile memorycard through a command bus, the first command indicating first data;transferring the first data by performing at least one of, transmittingthe first data from the host to the non-volatile memory card through oneor more data buses, and receiving, at the host, the first data from thenon-volatile memory card through the one or more data buses; andtransmitting a second command to the non-volatile memory card throughthe command bus during or before the transfer of the first data.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of example embodiments willbecome more apparent by describing in detail example embodiments withreference to the attached drawings. The accompanying drawings areintended to depict example embodiments and should not be interpreted tolimit the intended scope of the claims. The accompanying drawings arenot to be considered as drawn to scale unless explicitly noted.

FIG. 1 is a block diagram of a non-volatile memory card system accordingto some example embodiments of the inventive concepts;

FIG. 2 is a block diagram of a host controller illustrated in FIG. 1according to some example embodiments of the inventive concepts;

FIG. 3 is a block diagram of an embedded multimedia card (eMMC)according to some example embodiments of the inventive concepts;

FIG. 4A is a diagram of an example of a device command registerillustrated in FIG. 3;

FIG. 4B is a diagram of an example of command information stored in aregister illustrated in FIG. 4A;

FIG. 5 is a diagram of another example of the device command registerillustrated in FIG. 3;

FIG. 6 is a diagram of a command bus state machine according to someexample embodiments of the inventive concepts;

FIG. 7 is a diagram of a data bus state machine according to someexample embodiments of the inventive concepts;

FIG. 8 is a flowchart of a method of operating a non-volatile memorycard system according to some example embodiments of the inventiveconcepts;

FIG. 9 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according tosome example embodiments of the inventive concepts;

FIG. 10 is a schematic timing chart illustrating the operations of anon-volatile memory card system according to some example embodiments ofthe inventive concepts;

FIG. 11 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according toother example embodiments of the inventive concepts;

FIG. 12 is a schematic timing chart for the comparison between aconventional write operation of an eMMC and a write operation accordingto some example embodiments of the inventive concepts;

FIG. 13 is a flowchart of a read operation according to further exampleembodiments of the inventive concepts;

FIG. 14 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according toother example embodiments of the inventive concepts;

FIG. 15 is a flowchart of a write operation according to other exampleembodiments of the inventive concepts; and

FIG. 16 is a schematic timing chart for the comparison between aconventional write operation of an eMMC and a write operation accordingto further example embodiments of the inventive concepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example embodiments of the inventive concepts will now be described morefully hereinafter with reference to the accompanying drawings, in whichembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Inthe drawings, the size and relative sizes of layers and regions may beexaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed itemsand may be abbreviated as “/”.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first signal could be termed asecond signal, and, similarly, a second signal could be termed a firstsignal without departing from the teachings of the disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” or “includes” and/or “including” when used in thisspecification, specify the presence of stated features, regions,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,regions, integers, steps, operations, elements, components, and/orgroups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and/orthe present application, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

The embedded multimedia card (eMMC), electrical standard (version 4.51),i.e., JESD84-B451, published by the Joint Electron Devices EngineeringCouncil (JEDEC) (http://www.jedec.org) in June 2012 is herebyincorporated by reference. Accordingly, unless otherwise defined, termsand definitions used herein have the same meaning as defined in theJESD84-B451.

Various example embodiments of the inventive concepts include lines (orchannels) in addition to an existing 10-wire bus in order to increasenoise immunity and a transmission speed of data transferred between ahost and a device.

Herein, a channel transmitting a signal or a voltage may be a host pad,an eMMC pad, a bus, a line, a driver (including a differential amplifierin some embodiments), a receiver (including a differential amplifier insome embodiments), or a combination of at least two thereof. Thefunctions of the lines and circuits and methods for generating a signaltransmitted through the lines will be described in detail hereinafter.

Unless explicitly otherwise described with a specific intention, thepropagation delay of a functional circuit such as a bus, a wire, a pad(or a pin), a driver, a receiver, and/or a differential amplifier is notconsidered for convenience' sake in the description.

FIG. 1 is a block diagram of an eMMC system 100 according to someexample embodiments of the inventive concepts. The eMMC system 100includes a host 200 and a device 300. The device 300 is a non-volatilememory card such as a secure digital (SD) card, MMC or eMMC. However,example embodiments of the inventive concepts are not restrictedthereto.

In some example embodiments of the inventive concepts, the device 300 isan eMMC.

The host 200 may control data processing operations such as a data readoperation and a data write operation. The data processing operations maybe performed at a single data rate (SDR) or a double data rate (DDR).

The host 200 may be a data processing device, such as a centralprocessing unit (CPU), a processor, a microprocessor, or an applicationprocessor, which can process data. The data processing device may beembedded or implemented in an electronic device. The electronic devicemay be implemented as a personal computer (PC), a laptop computer, amobile telephone, a smart phone, a tablet PC, a personal digitalassistant (PDA), an enterprise digital assistant (EDA), a digital stillcamera, a digital video camera, an audio device, a portable multimediaplayer (PMP), a personal navigation device or portable navigation device(PND), an MP3 player, a handheld game console, or an e-book.

The eMMC 300 may be electrically connected with the electronic devicethrough connection means (e.g., pads, pins, buses, or communicationlines) to communicate with the host 200A.

The host 200 may include a processor 215, a memory 220, and a hostcontroller 230. An operating system (OS)/host firmware 210 may be drivenby the processor 215. The memory 220 may include a DRAM and a SRAM.

The host 200 may also include a clock generator (not shown). The clockgenerator generates a clock signal CLK used in the host 200 and the eMMC300. The clock generator may be implemented by a phase locked loop(PLL).

The processor 215 may be hardware that controls the generation of acommand CMD, the analysis of a response RES, the process of data storedin an extended card specific data (CSD) register (or an EXT CSDregister) 371, and/or the process of other data. The processor 215 maydrive the OS/host firmware 210 to perform these operations.

The host controller 230 interfaces with the eMMC 300. The hostcontroller 230 issues the command CMD to the eMMC 300, receives theresponse RES to the command CMD, transmit write data to the eMMC 300,and receives read data from the eMMC 300.

The host controller 230 may include host command registers 235 forstoring information about commands transmitted to the eMMC 300. The hostcommand registers 235 may be provided separated from a memory (e.g.,220) within the host 200 or may be provided in the memory (e.g., 220).

The eMMC buses illustrated in FIG. 1 may include ten conventional buses101, 102, and 103 (for example, defined in eMMC 4.51). However, exampleembodiments of the inventive concepts are not restricted thereto. Forinstance, eMMC buses may also include a unidirectional return clock bus(not shown) that transmits a return clock signal (not shown) from theeMMC 300 to the host 200.

The clock bus 101 transmits the clock signal CLK. The bidirectionalcommand bus 102 transmits the command CMD to the eMMC 300 and transmitsthe response RES to the command CMD to the host 200. The bidirectionaldata bus 103 transmits write data DAT[7:0] to the eMMC 300 for the datawrite operation and transmits read data DAT[7:0] to the host 200 for thedata read operation.

The host 200 may transmit a hardware reset signal to the eMMC 300through a reset line (not shown). The host 200 may generate operatingvoltages necessary for the operations of the eMMC 300 and transmit themto the eMMC 300.

FIG. 2 is a block diagram of the host controller 230 illustrated in FIG.1 according to some example embodiments of the inventive concepts. Thehost controller 230 includes a command generation unit 231, a datainput/output (I/O) unit 234, a task management unit 232, and a statecontrol unit 233. The task management unit 232 may manage the creationand termination of a task.

The command generation unit 231 may generate the command CMD at therequest of a task and send the command CMD to the eMMC 300. It may alsoreceive the response RES to the command CMD.

The data I/O unit 234 may transmit the data DAT[7:0] to the eMMC 300through the bidirectional data buses 103 in a write operation and mayreceive the data DAT[7:0] from a flash memory 370 through thebidirectional data buses 103 in a read operation.

The state control unit 233 may independently control a command bus statemachine for managing the state of the command bus 102 and a data busstate machine for managing the state of the data bus 103. The operationof the state control unit 233 will be described with reference to FIGS.6 and 7 later.

The elements of the host controller 230 illustrated in FIG. 2 may beimplemented in hardware, software, or a combination thereof. Forinstance, some or all of the elements of the host controller 230 may beimplemented in firmware.

FIG. 3 is a block diagram of the eMMC 300 according to some exampleembodiments of the inventive concepts. Referring to FIG. 3, the eMMC 300includes a device controller, e.g., an eMMC controller, 310 and theflash memory 370.

The eMMC controller 310 controls data communication between the host 200and the flash memory 370. The eMMC controller 310 includes an eMMC hostinterface 320, a CPU 330, a memory 340, an error correction code (ECC)block 360, and a flash interface 365.

The eMMC host interface 320 receives the clock signal CLK and thecommand CMD from the host 200, interprets the command CMD, generates theresponse RES according to an interpretation result, and transmits theresponse RES and data generated based on the response RES to the host200. The eMMC host interface 320 may include a device command register325 for storing information about commands received from the host 200.The device command register 325 may be implemented separately from amemory (e.g., 340) within the device controller 310 or may beimplemented using the memory.

FIG. 4A is a diagram of an example 325A of the device command register325 illustrated in FIG. 3. The device command register 325A includes Nregisters 325-1 through 325-N where N is a natural number of at least 2and indicates the size of the device command register 325A, i.e., thenumber of registers included in the device command register 325A. Here,N is defined as a multi-queue depth. Accordingly, the eMMC hostinterface 320 may receive up to as many commands as a maximummulti-queue depth from the host 200 and store the commands in theregisters 325-1 through 325-N, respectively.

A command according to the current embodiments is a command predefinedbetween the host 200 and the eMMC 300 to allow a command received fromthe host 200 to be stored in the eMMC 300 so that before an operationcorresponding to a current command is completed (for example, beforedata read from the flash memory 370 is transmitted to the host 200 orbefore data received from the host 200 is programmed to the flash memory370), a subsequent command can be received.

In other words, the command according to the current embodiments is nota conventionally defined command in an eMMC but is newly defined commandin order to increase an overall data transfer rate by allowing the eMMC300 to receive another command even in a busy state (e.g., a data readoperation or a data write operation).

According to a conventional eMMC protocol, during data transfer or whilethe eMMC is in the busy state, a host cannot send commands (a readcommand and a write command) other than a stop or abort command and astatus check command to an eMMC. The stop or abort command is forstopping data transfer and the status check command is for checking thestate of a device. For instance, according to the conventional eMMCprotocol, commands cannot be transmitted in a send-data state, areceive-data state, and a program state and can be transmitted only in atransfer state after the completion of an operation. Therefore,performance decreases due to protocol overhead.

According to the example embodiments of the inventive concepts, evenduring the data transfer or the busy state of the eMMC 300, the host 200can send a command to the eMMC 300 so that the eMMC 300 prepares forsubsequent data transmission, thereby increasing data transferperformance. A command according to the example embodiments of theinventive concepts may not be the stop or abort command or the statuscheck command but may be a preparation command for preparation ofsubsequent data transfer, a command for canceling the preparationcommand, or a command for reading data prepared in response to thepreparation command. Commands may be stored in the registers 325-1through 325-N illustrated in FIG. 4A.

The registers 325-1 through 325-N store information (hereinafter,referred to as command information) about a command issued from the host200. For instance, the eMMC host interface 320 may store informationabout a first command in the first register 325-1 and store informationabout a second command in the second register 325-2. In this manner, theeMMC host interface 320 may store command information about up to Ncommands in the registers 325-1 through 325-N.

FIG. 4B is a diagram of an example of command information stored in theregister 325-N illustrated in FIG. 4A. The command information mayinclude a command type, an address, and a data size. However, exampleembodiments of the inventive concepts are not restricted to the currentembodiments. The command type, the address, and the data size may beincluded in a command issued by the host 200 and transferred to the eMMC300.

The command type is a field indicating a type of a command and mayinclude a prepare-read command and a prepare-write command. The addressindicates an address at which the command is executed. The data sizeindicates the size of data on which the command is executed. Forinstance, when the command is a prepare-read command, the address is100, and the data size is 1024; it may instruct to read data of 1024bytes at an address of 100. However, the unit of a data size is notrestricted to bytes. A different unit such as the number of blocks orpages of a predetermined size may be used.

FIG. 5 is a diagram of another example 325B of the device commandregister 325 illustrated in FIG. 3. The device command register 325B mayinclude data size registers 326-1 through 326-N respectively storingdata sizes DS1 through DSN and address registers 327-1 through 327-Nrespectively storing start addresses SA1 through SAN. The data sizes DS1through DSN and the start addresses SA1 through SAN may be informationincluded in commands.

In the example embodiments of the inventive concepts, a command mayinclude a command (hereinafter, referred to as a size specifyingcommand) for specifying the size of data to be read or written and acommand (hereinafter, referred to as an address specifying command) forspecifying a start address indicating the position of the data.

The size specifying command may include a command type and a data size.The command type is a field or an argument that indicates a type ofcommand. The data size may be a block count, but example embodiments ofthe inventive concepts are not restricted thereto. A block is a dataunit with a predetermined size and may correspond, for instance, to apage of flash memory. However, example embodiments of the inventiveconcepts are not restricted thereto. The data size of the sizespecifying command may be stored in a corresponding one of the data sizeregisters 326-1 through 326-N.

The address specifying command may include a command type and a startaddress. The start address in the address specifying command may bestored in a corresponding one of the address registers 327-1 through327-N.

The host command register 235 of the host 200 may be similar to thedevice command register 325A or 325B illustrated in FIG. 4A or 5.

The host controller 230 may include the host command register 235 thatmanages commands transmitted to the eMMC 300 to store commandinformation.

The CPU 330 controls the operations of the interfaces 320 and 365 andcontrols the overall operation of the eMMC 300. The memory 340temporarily stores data transferred between the interfaces 320 and 365.The memory 340 may be implemented by volatile memory.

The flash memory 370 stores data. When the flash memory 370 isimplemented by NAND flash memory, the flash interface 365 may beimplemented by a NAND flash interface. The flash memory 370 includes theEXT_CSD register 371 that stores device properties and selected modes.

The flash memory 370 may include a plurality of memory elements CE0through CE3. Although four memory elements CE0 through CE3 areillustrated in FIG. 3, example embodiments of the inventive concepts arenot restricted to the current embodiments. The flash memory 370 may havea structure that supports at least two channels. The host 200 may issueSEND_EXT_CSD (CMD8) to read the EXT_CSD register 371. The eMMC 300transmits data in the EXT_CSD register 371, which is 512 bytes inlength, as a data block to the host 200. A multi-queue depth may be setin a reserved field of the EXT_CSD register 371. Alternatively, themulti-queue depth may be set in another host control register, which canbe controlled or set by the host 200.

FIG. 6 is a diagram of a command bus state machine according to someexample embodiments of the inventive concepts. FIG. 7 is a diagram of adata bus state machine according to some example embodiments of theinventive concepts.

Referring to FIG. 6, a command bus state may be an idle state S10, atransmit-command state S11, or a receive-response state S13. However,the command bus state is not restricted to these three states in FIG. 6.When there is a command to be transmitted to the eMMC 300, the hostcontroller 230 switches the command bus state from the idle state S10 tothe transmit-command state S11 so that the command is transmitted to theeMMC 300. After the command is transmitted to the eMMC 300, the commandbus state is switched to the receive-response state S13 when the commandexpects a response. When the response to the command is received fromthe eMMC 300, the command bus state is switched to the idle state S10.When the command does not expect a response, the command bus state isswitched from the transmit-command state S11 to the idle state S10. Astand-by state (not shown) lasting during a predetermined number ofclock cycles may be intervened in the transition from thereceive-response state S13 to the idle state S10 and the transition fromthe transmit-command state S11 to the idle state S10.

Referring to FIG. 7, a data bus state may be an idle state S20, a datatransfer state S21, or a receive-response or wait state, andspecifically, a receive-cyclic redundancy check (CRC) status or waitstate S22. However, the data bus state is not restricted to these threestates in FIG. 7. When the host controller 230 transmits a commandaccompanied by data transfer (hereinafter, referred to as a datatransfer command) to the eMMC 300, the data bus state is switched fromthe idle state S20 to the data transfer state S21 so that datacorresponding to the data transfer command is transmitted to the eMMC300. The data may be transmitted in units of blocks. For instance, whenthe transmission of data of a block is completed, the data bus state isswitched to the receive-CRC status or wait state S22 and the hostcontroller 230 stands by until receiving a CRC status responsecorresponding to the block.

When receiving the CRC status response, the host controller 230 switchesinto the data transfer state S21 and transmits data of a next block andthen switches into the receive-CRC status or wait state S22. When thetransmission of data of all blocks is completed, the host controller 230switches into the idle state S20.

The state control unit 233 independently operates the command bus statemachine and the data bus state machine. It is apparent that the commandbus state and the data bus state may be related with each other.However, the command bus state and the data bus state are not operatedin a single state machine but are operated in separate machines,respectively.

For instance, even when the data bus state is not an idle state, thatis, the data bus state is a data transfer state or receive-CRC status orwait state, the host 200 may transmit a command (e.g., a command that isnot accompanied by data transfer, a cancel command, or the like) to thyeMMC 300. A command may be largely divided into two types: one is a datatransfer command; and the other is a command that is not accompanied bydata transfer (hereinafter, referred to as a non-data transfer command).

FIG. 8 is a flowchart of a method of operating a non-volatile memorycard system according to some example embodiments of the inventiveconcepts. The method may be performed using the non-volatile memory cardsystem 100 illustrated in FIG. 1.

The host 200 transmits a prepare-read (PR) command to the devicecontroller 310 in operation S110. The device controller 310 may send anR1 response to the host 200 in response to the PR command in operationS115 and store PR command information in a command register.

The PR command instructs the eMMC 300 to prepare a data read operationand is a non-data transfer command. The PR command may be transmitted tothe device controller 310 even while data is being transmitted or theeMMC 300 is in a busy state. In addition, a plurality of (e.g., amulti-queue depth) PR commands may be transmitted. In other words,operations S110 and S115 may be repeated multiple times. The host 200may also include a command counter (not shown) to count the number of PRcommands transmitted.

The PR command may include a data size specifying the size of data to beread and a start address specifying a start address of the data. Thedata size and the start address may be stored in the command register325A or 325B as shown in FIG. 4A or FIG. 5.

The device controller 310 sends a read command to the flash memory 370according to the start address and the data size stored in the commandregister 325 in operation S120 and reads data from the flash memory 370in operation S125. The read data is stored in a data buffer in operationS130.

The data buffer is provided to store data according to a PR command. Thememory 340 shown in FIG. 3 may be used as the data buffer.

When previous data transfer is completed (i.e., it is YES) in operationS135, the host 200 transmits a data read-out (RO) command to the devicecontroller 310 in operation S140. In response to the data RO commandfrom the host 200, the device controller 310 sends an R1 response to thehost 200 in operation S145 and transmits the data in the data buffer tothe host 200 in operation S150.

The data RO command instructs the data, which has been stored in thedata buffer according to the PR command, to be transmitted to the host200. It is a data transfer command. The data RO command may betransmitted to the eMMC 300 when the data bus state is the idle stateafter the previous data transfer is completed.

FIG. 9 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according tosome example embodiments of the inventive concepts. Part (a) in FIG. 9shows the conventional read operation and part (b) in FIG. 9 shows theread operation according to the current example embodiments of theinventive concepts.

Referring to part (a) in FIG. 9, when a host sends a read-read (RD)command 911 to an eMMC through a command bus, the eMMC reads (912) datafrom a flash memory in response to the RD command 911 and transmits(913) the data to the host through a data bus DAT. The host receives theread data through the data bus DAT and stores (914) it in a host memory.

Only after receiving (913) the data corresponding to the RD command 911,the host can send a next RD command 915 to the eMMC. Accordingly, thehost is forced to wait for the data to be received (913) after sendingthe RD command 911.

Referring to part (b) in FIG. 9, the host 200 sends a first PR command921 to the eMMC 300. The eMMC 300 reads data from a flash memory inresponse to the first PR command 921 and stores (922) the data in a databuffer.

The host 200 sends a data RO command 923 to the eMMC 300 in order toread the data from the data buffer. The eMMC 300 transmits (924) thedata stored in the data buffer to the host 200 through the data bus DATin response to the data RO command 923. The host 200 receives the datathrough the data bus DAT and stores (925) it in a host memory.Meanwhile, before the data transfer 924 is completed, that is, while thedata is being transferred (924), the host 200 sends a next PR command926 to the eMMC 300, so that the eMMC 300 can prepare a next readoperation. The eMMC 300 reads data from the flash memory and stores(927) it in the data buffer in response to the PR command 926.

In this manner, the host 200 sends a PR command to the eMMC 300 evenwhile data is being transferred or the eMMC 300 is in the busy state toallow the eMMC 300 to prepare data for a next read operation, therebyincreasing data read performance. In other words, since the eMMC 300receives the PR command in advance and prepares for the next readoperation (for example, the eMMC 300 reads data from the flash memoryand stores it in the data buffer), thereby increasing the readperformance.

In the embodiments shown in part (b) in FIG. 9, the data RO commandcorresponds to the PR command one on one, but example embodiments of theinventive concepts are not restricted to the current embodiments. Inother embodiments, all of read data prepared using a plurality of PRcommands may be transmitted to the host 200 at a time using a singledata RO command.

FIG. 10 is a schematic timing chart illustrating the operations of thenon-volatile memory card system 100 according to some exampleembodiments of the inventive concepts. The host 200 sends a first PRcommand 951 to the eMMC 300. The eMMC 300 reads data from a flash memoryin response to the first PR command 951 and stores (952) the data in adata buffer.

The host 200 sends a data RO command 953 to the eMMC 300 in order toread the data from the data buffer. The eMMC 300 transmits (954) thedata stored in the data buffer to the host 200 through the data bus DATin response to the data RO command 953. The host 200 receives the datathrough the data bus DAT and stores (956) it in a host memory.

During the data transfer (954), the host 200 consecutively sends asecond PR command 957 and a third PR command 959 to the eMMC 300. TheeMMC 300 reads data from the flash memory and stores (958) it in thedata buffer in response to the second PR command 957 and reads data fromthe flash memory and stores (961) it in the data buffer in response tothe third PR command 959. The host 200 may cancel the third PR command959 before reading the data from the data buffer.

For instance, the host 200 may send the eMMC 300 a cancel command 960for cancelling the third PR command 959. The cancel command 960 mayspecifically cancel part or all of previous PR commands. The eMMC 300cancels the third PR command 959 in response to the cancel command 960.For instance, when the cancel command 960 is received before datacorresponding to the third PR command 959 is read from the flash memory,the third PR command 959 may be removed from a command register withouta data read operation being performed. When the cancel command 960 isreceived after the data is read in response to the third PR command 959and is stored in the data buffer, the data in the data buffer may beremoved or invalidated.

The host 200 sends a data RO command 962 to the eMMC 300 in order toread the data from the data buffer. The eMMC 300 transmits (963) thedata 958 stored in the data buffer to the host 200 through the data busDAT in response to the data RO command 962. The host 200 receives thedata through the data bus DAT and stores (964) it in the host memory.

FIG. 11 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according toother example embodiments of the inventive concepts. Part (a) in FIG. 11shows the conventional read operation and part (b) in FIG. 11 shows theread operation according to the example embodiments of the inventiveconcepts.

Referring to part (a) in FIG. 11, when a host sends an RD command 411 tothe eMMC through a command bus, the eMMC sends an R1 response 412 to theRD command 411 to the host through the command bus. The eMMC prepares(431) to read data from a flash memory NAND in response to the RDcommand 411, reads (432 and 433) data from flash memory cells, andtransmits (421) the data to the host through data buses.

The host can send a subsequent RD command 414 only after receiving thedata 421 corresponding to the RD command 411. Accordingly, the host isforced to stand by (413) until receiving the data 421 since receivingthe R1 response 412 to the RD command 411.

However, referring to part (b) in FIG. 11, the host 200 sends a first PRcommand 441 to the eMMC 300. The eMMC 300 sends to the host 200 an R1response 442 to the first PR command 441. Also, the eMMC 300 reads (461and 462) data from the flash memory CE0 in response to the first PRcommand 441 and stores (463) the data in a data buffer.

Upon receiving the R1 response 442 from the eMMC 300, the host 200 sendsa second PR command 443 to the eMMC 300. In other words, the host 200can send the second PR command 443 for reading next data to the eMMC 300in a state where data corresponding to the first PR command 441 has notbeen received yet.

The eMMC 300 sends an R1 response 444 to the second PR command 443 tothe host 200 and also reads (471 and 472) data from the flash memory CE1in response to the second PR command 443 and stores (473) the data inthe data buffer.

In this manner, the host 200 can send up to as many PR commands as amaximum multi-queue depth N. For instance, when the multi-queue depth Nis 4, the host 200 may send up to four PR commands. The multi-queuedepth N may be stored in the EXT_CSD register 371 of the eMMC 300. Thehost 200 may read the EXT_CSD register 371 using a particular command,e.g., SEND_EXT_CSD, and recognize the multi-queue depth N.

The eMMC 300 may read data from the flash memory 370 using a paralleloperation. For instance, the eMMC 300 may perform in parallel anoperation (461 through 463) of reading data from the first memoryelement CE0 of the flash memory 370 and an operation (471 through 473)of reading data from the second memory element CE1 of the flash memory370 using a multi-plane read operation.

The host 200 sends a data RO command 445 to the eMMC 300 in order toread out the data stored in the data buffer. The eMMC 300 sends an R1response 446 to the data RO command 445 and also transfers the datastored in the data buffer to the host 200 through data buses. At thistime, the data 451 transferred may be data 463 read from the flashmemory CE0 in response to the first PR command 441. The data RO command445 may be a command newly defined between the host 200 and the eMMC 300for a data read operation according to some example embodiments of theinventive concepts.

The host 200 sends a data RO command 447 to the eMMC 300 in order toread out the next data stored in the data buffer. The eMMC 300 sends anR1 response to the data RO command 447 and also transfers the datastored in the data buffer to the host 200 through the data buses. Atthis time, the data 452 transferred may be data 473 read from the flashmemory CE1 in response to the second PR command 443.

As described above, according to the example embodiments of theinventive concepts, an idle time between commands is reduced, so thatread performance is increased. In other words, the eMMC 300 receives PRcommands in advance and makes preparations for read operations (e.g.,preparations of reading data from the flash memory 370 and storing thedata in the data buffer) at a time or in parallel, thereby increasingthe read performance.

FIG. 12 is a schematic timing chart for the comparison between aconventional write operation of an eMMC and a write operation accordingto some example embodiments of the inventive concepts. Part (a) in FIG.12 shows the conventional write operation and part (b) in FIG. 12 showsthe write operation according to the example embodiments of theinventive concepts.

Referring to part (a) in FIG. 12, when a host sends a write (WR) command511 to the eMMC through a command bus, the eMMC sends an R1 response 512to the WR command 511 to the host through the command bus. Uponreceiving the R1 response 512, the host transfers (521) data relatedwith the WR command 511 to the eMMC through data buses. The eMMCprograms (525) the data received from the host to a flash memory. Untilthe eMMC completes the programming of the data to the flash memory, theeMMC is in a busy state. The eMMC may inform the host of the busy statethrough one (e.g., DAT[0]) of the data buses. The host can send asubsequent WR command 514 to eMMC only after standing by (513) until thedata writing to the flash memory is completed.

However, referring to part (b) in FIG. 12 according to the exampleembodiments of the inventive concepts, the host 200 sends a first WRcommand 531 to the eMMC 300. The eMMC 300 sends to the host 200 an R1response 532 to the first WR command 531.

Upon receiving the R1 response 532, the host 200 transfers (541) datarelated with the first WR command 531 to the eMMC 300 through data busesand may also send a second WR command 533 to the eMMC 300 whiletransferring the data. The eMMC 300 may receive the second WR command533 from the host 200 and send an R1response 534 to the host 200 beforeit completely programs (545) the data 541 related with the first WRcommand 531 to the flash memory 370.

In this manner, the host 200 may send up to as many WR commands as themaximum multi-queue depth N. For instance, when the multi-queue depth Nis 4, the host 200 may send up to four WR commands.

The eMMC 300 may sequentially write (545 and 546) data to the flashmemory 370. In other embodiments, the eMMC 300 may write data to theflash memory 370 using a parallel operation. For instance, the eMMC 300may perform in parallel an operation of programming data to the firstmemory element CE0 of the flash memory 370 and an operation ofprogramming data to the second memory element CE1 of the flash memory370 using a multi-plane program operation.

FIG. 13 is a flowchart of a read operation according to further exampleembodiments of the inventive concepts. The host 200 sends the devicecontroller 310 a size specifying command CMD_ds for specifying the sizeof data to be read in operation S510. In response to the size specifyingcommand CMD_ds, the device controller 310 sends an R1 response to thehost 200 in operation S515 and stores a data size included in the sizespecifying command CMD_ds in the device command register 325.

After receiving the R1 response from the eMMC 300, the host 200 sends anaddress specifying command CMD_sa to the device controller 310 inoperation S520. The device controller 310 sends an R1 response to thehost 200 in response to the address specifying command CMD_sa inoperation S525 and stores a start address in the device command register325.

Operations S510 through S525 may be repeated up to as many times as themaximum multi-queue depth N and may be performed even while previousdata is being transferred through data buses.

The size specifying command CMD_ds and the address specifying commandCMD_sa may correspond to a PR command that has been described above. Inother words, the PR command may be implemented as a command setincluding at least two commands.

The device controller 310 sends a read command to the flash memory 370according to the start address and the data size stored in the devicecommand register 325 in operation S530 and reads data from the flashmemory 370 in operation S540. The device controller 310 stores the datain a data buffer in operation S545.

When previous data transfer is completed (YES) in operation S550, thehost 200 sends a data read-out command CMD_ro to the device controller310 in operation S555. In response to the data read-out command CMD_ro,the device controller 310 sends an R1 response to the host 200 inoperation S560. In addition, the device controller 310 transmits thedata in the data buffer to the host 200 in operation S565. The dataread-out command CMD_ro may be the same as a data RO command describedabove.

FIG. 14 is a schematic timing chart for the comparison between aconventional read operation of an eMMC and a read operation according toother example embodiments of the inventive concepts. Part (a) in FIG. 14shows the conventional read operation and part (b) in FIG. 14 shows theread operation according to the example embodiments of the inventiveconcepts.

Referring to part (a) in FIG. 14, when a current state is a datatransfer state, that is, while data is being transferred (610) through adata bus, a host cannot send a command for reading or writing data fromor to a flash memory except for a particular command, e.g., a stopcommand or an abort command for stopping a previous command. Only afterthe data transfer 610 is completed, the host can send a normal readcommand 620 to an eMMC. The eMMC reads (tR or 625) data from the flashmemory in response to normal data read commands 621 and 623 andtransmits (627) the data to the host. While the eMMC is reading (625)the data from the flash memory and transmitting (627) the data to thehost, the host cannot send a subsequent read command. Therefore, thehost needs to wait for the data to be completely received since sendingthe read command.

However, referring to part (b) in FIG. 14, the host 200 sends a PRcommand 720 to the eMMC 300 even during data transfer 710. In detail,the host 200 sends a size specifying command, i.e., CMD57 721 to theeMMC 300 and the eMMC 300 sends to the host 200 an R1 response 722 tothe CMD57 721. Next, the host 200 sends an address specifying command,i.e., CMD58 723 to the eMMC 300 and the eMMC 300 sends to the host 200an R1 response 724 to the CMD58 723. Here, CMD57 721 corresponds to thesize specifying command CMD_ds illustrated in FIG. 13 and CMD58 723corresponds to the address specifying command CMD_sa illustrated in FIG.13. The PR command 720 is implemented as a command set including CMD57721 and CMD58 723. The host 200 may send a PR command including CMD57and CMD58 to the eMMC 300 N times where N is an integer of at least 1.

The eMMC 300 reads data from the flash memory 370 in response to the PRcommand 720 and stores the data in a data buffer. Meanwhile, the data710 being transferred may be stored in a normal buffer separated fromthe data buffer.

When the transfer of the previous data 710 is completed, the host 200sends a data read-out command, i.e., CMD59 726 to the eMMC 300 in orderto read out data 731 through 733 from the data buffer. The eMMC 300sends an R1 response 726 to the host 200 in response to the CMD59 726and transmits the data 731 through 733 stored in the data buffer to thehost 200 through data buses.

FIG. 15 is a flowchart of a write operation according to other exampleembodiments of the inventive concepts. The host 200 transmits a sizespecifying command CMD_ds for specify the size of data to be written tothe device controller 310 in operation S610. The device controller 310sends an R1 response to the host 200 in response to the size specifyingcommand CMD_ds in operation S615 and stores a data size corresponding tothe size specifying command CMD_ds in the device command register 325.

After receiving the R1 response from the eMMC 300, the host 200 sends anaddress specifying command CMD_sa to the device controller 310 inoperation 5S20. The device controller 310 sends an R1 response to thehost 200 in response to the address specifying command CMD_sa inoperation S625 and stores a start address in the device command register325.

Operations 5610 through S625 may be repeated up to as many times as themaximum multi-queue depth N and may be performed even while previousdata is being transferred through the data buses although not shown.Operations 5610 through S625 may also be performed even while the devicecontroller 310 is applying a program command to the flash memory 370 inoperation S630 for the programming of the previous data and isprogramming the previous data to the flash memory 370 in operation S640.At this time, the previous data that is being transferred or programmedto the flash memory 370 may be stored in the normal buffer.

When the transfer of the previous data is completed (i.e., YES) inoperation S650, the host 200 sends a data write-in command CMD_wr to thedevice controller 310 in operation S655. In response to the datawrite-in command CMD_wr from the host 200, the device controller 310sends an R1response to the host 200 in operation S660. Then, the host200 transfers the write data to the eMMC 300 in operation S665.

The eMMC 300 stores the write data in the data buffer in operation S670.The device controller 310 applies to the flash memory 370 a programcommand for the programming of the data stored in the data buffer inoperation S675 and programs the write data to the flash memory 370 inoperation S680.

In the embodiments illustrated in FIG. 15, the size specifying commandCMD_ds and the address specifying command CMD_sa may form aprepare-write command which is a sort of non-data transfer command thatis not accompanied by data transfer. The data write-in command CMD_wrmay be a data transfer command, which is accompanied by transfer ofwrite data.

FIG. 16 is a schematic timing chart for the comparison between aconventional write operation of an eMMC and a write operation accordingto further example embodiments of the inventive concepts. Part (a) inFIG. 16 shows the conventional write operation and part (b) in FIG. 16shows the write operation according to the example embodiments of theinventive concepts.

Referring to part (a) in FIG. 16, after the completion of the transferof previous data 811, a host sends an eMMC data 812, a write command821, and data DAT-a or 812 corresponding to the write command 821. TheeMMC programs (tPRG1) the data DAT-a or 812 to a flash memory. Only whenthe data DAT-a or 812 is completely programmed to the flash memory, thetransfer of the data DAT-a or 812 is completed. Accordingly, the hoststands by until the programming of the data DAT-a is completed and onlythen sends another write command 822 and data DAT-b or 813 correspondingto the write command 822 to the eMMC.

However, referring to part (b) in FIG. 16, the host 200 sendsprepare-write commands CS or 841 through 844 to the eMMC 300 even duringthe transfer of previous data 831. The prepare-write commands CS or 841through 844 may include a size specifying command CMD_ds and an addressspecifying command CMD_sa, as shown in FIG. 15.

The eMMC 300 sequentially receives and stores the prepare-write commandsCS or 841 through 844 in the device command register 325. When thetransfer and the programming (tPROG) of the previous data 831 iscompleted, the host 200 sends the eMMC 300 a data write-in command 845and data DAT-a, DAT-b, DAT-c, and DAT-d corresponding to the datawrite-in command 845. The eMMC 300 stores the data DAT-a, DAT-b, DAT-c,and DAT-d in the data buffer and programs the data DAT-a, DAT-b, DAT-c,and DAT-d stored in the data buffer to the flash memory 370.

In the example embodiments of the inventive concepts, an eMMC isexplained as an example. However, example embodiments of the inventiveconcepts are not restricted thereto but may be applied to anynon-volatile memory card including a command bus and a data bus and anyhost controlling the card.

As described above, according to some example embodiments of theinventive concepts, a host can send a command to eMMC during datatransfer or before the eMMC completes a read/write operation, so thatpreparation for a next read/write command is performed even during theread/write operation of the eMMC. As a result, the read/writeperformance of the eMMC is increased.

Example embodiments of the inventive concepts having thus beendescribed, it will be obvious that the same may be varied in many ways.Such variations are not to be regarded as a departure from the intendedspirit and scope of example embodiments of the inventive concepts, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A method of operating a host connected to anon-volatile memory card: transmitting a first command from the host tothe non-volatile memory card through a command bus, the first commandindicating first data; transferring the first data by performing atleast one of, transmitting the first data from the host to thenon-volatile memory card through one or more data buses, and receiving,at the host, the first data from the non-volatile memory card throughthe one or more data buses; and transmitting a second command to thenon-volatile memory card through the command bus during or before thetransfer of the first data.
 2. The method of claim 1, wherein the secondcommand is transmitted when the non-volatile memory card is in a busystate.
 3. The method of claim 2, wherein the busy state of thenon-volatile memory card is indicated by one of the one or more databuses.
 4. The method of claim 1, further comprising: operating a commandbus state machine for managing states of the command bus; and operatinga data bus state machine for managing states of the one or more databuses independently from the command bus state machine, wherein, thestates of the one or more data buses include an idle state, a datatransfer state, and a receive-response or wait state, and the secondcommand is transmitted to the non-volatile memory card when a state ofthe one or more data buses is the data transfer state or thereceive-response or wait state.
 5. The method of claim 1, wherein thefirst command is a command accompanied by data and the second command isa command that is not accompanied by data.
 6. The method of claim 1,further comprising: managing a number of times the second command istransmitted.
 7. The method of claim 6, further comprising: storing ahost multi-queue depth, the host multi-queue depth identifying a maximumnumber of times the second command can be transmitted.
 8. The method ofclaim 7, wherein the storing the host multi-queue depth comprises:reading information from an extended card specific data (CSD) registerof the non-volatile memory card; extracting a multi-queue depth from theinformation; and storing the extracted multi-queue depth as the hostmulti-queue depth.
 9. The method of claim 1, wherein the second commandis a prepare-read command including a data size indicating a size ofdata to be read and a start address.
 10. The method of claim 9, furthercomprising: transmitting a third command to the non-volatile memory cardto read data from a data buffer included in the non-volatile memorycard, wherein the non-volatile memory card reads the data from anon-volatile memory unit and stores the read data in the data buffer inresponse to the second command.
 11. The method of claim 10, wherein thethird command specifies all or part of the one or more second commandsand the non-volatile memory card transmits data to the host in responseto the third command, the data transmitted in response to the thirdcommand including only data that corresponds to the specified one ormore second commands.
 12. The method of claim 10, further comprising:transmitting a cancel command to the non-volatile memory card tospecifically cancel all or part of the one or more second commands. 13.The method of claim 1, wherein at least one of the one or more thesecond commands is a prepare-write command including a data sizeindicating a size of data to be written and a start address.
 14. Themethod of claim 13, further comprising: transmitting data correspondingto a first second command, from among the one or more second commands,to the non-volatile memory card through the one or more data buses,wherein a second one of the one or more second commands, is transmittedto the non-volatile memory card while the data corresponding to thefirst second command is being transmitted through the one or more databuses.
 15. The method of claim 13, further comprising: transmitting, tothe non-volatile memory card through the command bus, a third commandfor transmitting data corresponding to at least one of the one or moresecond commands; and transmitting the data corresponding to the at leastone second command to the non-volatile memory card through the one ormore data buses.
 16. A method of operating a non-volatile memory cardsystem including a host connected with a non-volatile memory cardthrough a clock bus, a command bus, and one or more data buses, themethod comprising: transmitting, from the host, a first command to thenon-volatile memory card through the command bus; transferring firstdata corresponding to the first command between the host and thenon-volatile memory card through the one or more data buses; andtransmitting, from the host, one or more second commands to thenon-volatile memory card through the command bus during the transfer ofthe first data.
 17. The method of claim 16, further comprising;sequentially receiving, at the non-volatile memory card, a plurality ofthe or more second commands and storing the plurality of second commandsin a command register, wherein the transmitting the one or more secondcommands to the non-volatile memory card includes the host transmittingthe plurality of second commands of to the non-volatile memory card, theplurality of second commands having the same command type.
 18. Themethod of claim 17 wherein, each of the plurality of second commands isa prepare-read command including a data size indicating a size of datato be read and a start address, and the data size and the start addressare stored in the command register.
 19. The method of claim 18, furthercomprising: reading, at the non-volatile memory card, data from anon-volatile memory unit and storing the read data in a data bufferincluded in the non-volatile memory card, in response to each secondcommand.
 20. The method of claim 19, further comprising: transmitting,from the host, a third command to the non-volatile memory card; andtransmitting, from the non-volatile memory card, the read data stored inthe data buffer to the host in response to the third command.
 21. Themethod of claim 20, wherein the data transmitted to the host in responseto the third command is data read from the non-volatile memory inresponse to the plurality of second commands.
 22. The method of claim17, further comprising: transmitting, from the host to the non-volatilememory card, a cancel command for canceling one or more of the pluralityof second commands; and invalidating, at the non-volatile memory card inresponse to the cancel command, at least one of, the one or more of theplurality of second commands specified by the cancel command, and datacorresponding to the one or more of the plurality of second commandsspecified by the cancel command.
 23. The method of claim 17, whereineach of the plurality of second commands is a prepare-write commandincluding a data size indicating a size of data to be written and astart address.
 24. The method of claim 23, further comprising:transmitting, from the host to the non-volatile memory, second datacorresponding to a first second command, from among the plurality ofsecond commands, through the one or more data buses; receiving thesecond data at the non-volatile memory card; programming the receivedsecond data to a non-volatile memory unit in response to the firstsecond command; transmitting, from the host, a second one of theplurality of second commands to the non-volatile memory card while thesecond data is being transmitted through the one or more data buses;transmitting, from the host, third data corresponding to the second oneof the plurality of second commands to the non-volatile memory cardthrough the one or more data buses after the second data is completelytransmitted; receiving the third data at the non-volatile memory card;and programming the received third data to the non-volatile memory inresponse to the second command.
 25. The method of claim 23, furthercomprising: transmitting, from the host to the non-volatile memory card,a third command through the command bus; sequentially transmitting, fromthe host to the non-volatile memory card, second data corresponding tothe plurality of second commands through the one or more data buses;receiving the second data at the non-volatile memory car; andprogramming the second data to a non-volatile memory unit in response tothe third command.
 26. A host connected with a non-volatile memory cardthrough a clock bus, a command bus, and one or more data buses, the hostcomprising: a processor configured to control overall operation of thehost; and a host controller configured to be electrically connected withthe processor and to interface with the non-volatile memory card,wherein the host controller is configured to, transmit a first commandto the non-volatile memory card through the command bus, transmit firstdata corresponding to the first command to the non-volatile memory cardthrough the data bus or receive the first data from the non-volatilememory card through the one or more data buses, and transmit a secondcommand to the non-volatile memory card through the command bus duringor before transfer of the first data.
 27. The host of claim 26, whereinthe host controller is configured such that the second command istransmitted when the non-volatile memory card is in a busy state. 28.The host of claim 26, wherein the host controller comprises: a statecontrol unit configured to operate a command bus state machine formanaging states of the command bus and to operate a data bus statemachine for managing states of the one or more data buses independentlyfrom the command bus state machine, the state control unit beingconfigured such that the states of the one or more data buses include anidle state, a data transfer state, and a receive-response or wait state,the host control unit being configured such that the second command istransmitted to the non-volatile memory card when a state of the one ormore data buses is the data transfer state or the receive-response orwait state.
 29. The host of claim 28, wherein the first command is acommand accompanied by data and the second command is a command that isnot accompanied by data.
 30. The host of claim 28, wherein the hostcontroller further comprises: a counter configured to manage a number oftimes the second command is transmitted.